package com.wemall.core.tools;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Md5Encrypt {
    private static final char[] DIGITS = { '0', '1', '2', '3', '4', '5', '6',
                                           '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
                                         };

    public static String md5(String text){
        MessageDigest msgDigest = null;
        try {
            msgDigest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e){
            throw new IllegalStateException(
                "System doesn't support MD5 algorithm.");
        }
        try {
            msgDigest.update(text.getBytes("utf-8"));
        } catch (UnsupportedEncodingException e){
            throw new IllegalStateException(
                "System doesn't support your  EncodingException.");
        }

        byte[] bytes = msgDigest.digest();

        String md5Str = new String(encodeHex(bytes));

        return md5Str;
    }

    public static char[] encodeHex(byte[] data){
        int l = data.length;

        char[] out = new char[l << 1];

        int i = 0;
        for (int j = 0; i < l; i++){
            out[(j++)] = DIGITS[((0xF0 & data[i]) >>> 4)];
            out[(j++)] = DIGITS[(0xF & data[i])];
        }

        return out;
    }

    private static String byteArrayToHexString(byte b[]){
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++)
            resultSb.append(byteToHexString(b[i]));

        return resultSb.toString();
    }

    private static String byteToHexString(byte b){
        int n = b;
        if (n < 0)
            n += 256;
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    public static String MD5Encode(String origin, String charsetname){
        String resultString = null;
        try {
            resultString = new String(origin);
            MessageDigest md = MessageDigest.getInstance("MD5");
            if (charsetname == null || "".equals(charsetname))
                resultString = byteArrayToHexString(md.digest(resultString
                                                    .getBytes()));
            else
                resultString = byteArrayToHexString(md.digest(resultString
                                                    .getBytes(charsetname)));
        } catch (Exception exception){
        }
        return resultString;
    }

    private static final String hexDigits[] = { "0", "1", "2", "3", "4", "5",
            "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"
                                              };
}
